Twenty four Friesian cows at 2^nd lactating season with average live body weight (LBW) 383 Kg. Animals were randomly distributed into four similar groups (6 animal each), to be fed concentrate feed mixture (CFM) containing cotton seed cake or soybean meal or DDGS as a source of protein in rations B, C and D, respectively compared to that containing each of them in ration A as a control ration.Feeding trial lasted about 210 days and animals fed CFM, berseem hay and rice straw with rate of 60, 25 and 15% respectively. These proportions were chosen to achieve approximately isonitrogenous rations containing a bout 13 % CP. The results obtained showed that digestibility coefficient of OM,CP,EE and NFE for ration D (containing DDGS) showed significant (P<0.05) higher than the others, while differences in DM and CF digestibility were higher significant (P<0.05) with feeding on ration C than A or B but without significant effect with ration D. Feeding values for ration D expressed as TDN (%), DCP (%), DE and ME (M cal / Kg DM) were significant (P<0.05) higher than the other rations. Ration D containing DDGS tended to significant (P<0.05) increased for both actual milk (9.028 kg) and 4% FCM yield (8.906 kg) and improved milk composition and their yields than rations A and B. Feed efficiency as kg DM/Kg actual milk or kg 4% FCM yields was the best with ration D, than  the other rations. Ration D showed the cheapest feed cost to get one kg actual milk (2.072 LE) or  kg 4% FCM yield (2.100 LE). Also, ration D gave the highest net revenue (35.464 LE) and economical efficiency (1.90). The mean values of the  NH₃-N, Total –N and NPN (mg/100ml) concentrations were significant (P<0.05) higher by feeding on ration D. Blood parameters showed that there were no adverse effects, however these parameters  were within the normal values.